Motor vehicle drivetrain efficiency is constantly being improved, with a major advancement involving hybrid technology using a gasoline engine with a battery storage system and an electric motor. Current designs have included a regenerative braking feature that uses electric motor braking in order to recharge the storage batteries. Improved fuel economy is obtained by use of a relative small gasoline engine operating alternately with the electric motor. When the driver indicates demand for more power, both the gas and electric are utilized. The thermal efficiency of this design is the cumulative result of the gasoline engine, engine driven generator, storage battery, and electric motor. Each component reduces the overall efficiency. The regenerative braking recaptures some of this energy and is dependent on driving patterns. The more stop-and-go driving, the more regenerative braking will contribute to overall efficiency. Overall thermal efficiency is less than that of a gas engine alone but the lower average power results in better fuel economy.
All patents discovered involve gas-electric designs. No patents have been discovered that pertain to inertial (flywheel) storage.
Continuously variable transmissions date back at least 100 years, with most designs involving either pulley flange adjustments, or sliding gear arrangements. No patents were identified using the cog belt and high friction mated cones to accomplish ratio changes.
The following transmission designs were identified
Patent NumberInventor6,055,880GogovitzaMay 2, 20001,868,676StoeckichtJul. 26, 1932JP 200,133,0101Kino and OtaniNov. 30, 20016,349,607GogovitzaFeb. 26, 20024,533,011HeidemeyerAug. 6, 1985D 19, 917,276Lauer and HofmannOct. 26, 200053,202WaitMar. 13, 1866
Specific problems with gas-electric hybrids include cost, weight of batteries and electric motor, and overall thermal efficiency are issues related to the current design approach. Motor vehicles currently available are reported to cost the manufacturer significantly more than the selling price. Battery disposal is also an issue that must be addressed in the future.